The invention concerns a rearview mirror for vehicles, in particular, for commercial vehicles in which the mirror possesses an optical imaging apparatus.
U.S. Pat. No. 4,882,565 discloses a rearview mirror for vehicles in which an indicator device is integrated in the reflecting surface. The indicator device is provided with light from an illumination element located behind the mirror surface. With this device, simple warning signals or stylized presentations of various functional units can be presented and brought to the rearview mirror for attention. The images produced by a camera are not presented here.
Upon making a turn with a vehicle from a subordinate street into a main thoroughfare, normally the driver makes use of the rearview mirror before he turns. In the case of a right turn, he has not only the right side mirror with the visible rearward area but also the view to the right-front over the mirror in his field of sight. To be aware of risks or traffic on the left side, he must turn his head and if necessary, use the left rearview mirror. In heavy traffic, therefore, he is obliged to change both his direction of vision and the position of his head. Thus, while he is looking to one side, the other side is not being tended to. This can lead to dangerous situations.
The present invention develops a rearview mirror with an optical imaging device of such a nature that the disparate areas surrounding the vehicle will come to the attention of the driver.
The achievement of this objective is accomplished by the features of this invention.
By means of the provision of a monitor, which is placed in the rearview mirror, an image produced by an imaging device such as a camera can be transmitted to the monitor. The camera can be directed to a field of view, which is not in the view angle of the driver when he looks into the mirror. With the advantage of the invention, the driver in one glance can not only discern the area directly in the reflected angle of the mirror as well as the area in front of the mirror, but he can also see another area on the monitor in the mirror without needing to change his direction of view nor to turn his head. In the case of the monitor, advantageously a Liquid Crystal Display (LCD) image is employed. Likewise, the camera would advantageously be a charge-coupled device (CCD) camera.
In accord with an advantageous embodiment of the invention, the monitor is placed in the edge area of the mirror, that is, the mirror pane, in order not to interfere with the fundamental purpose of the mirror. This makes it possible that the monitor need not be integrated into the mirror pane but rather can be placed in a position under, beside or above the mirror pane. The placement of the monitor would be effected by an appropriate recess in the mirror housing.
In accord with another advantageous embodiment of the invention, the camera is likewise installed within the mirror housing, whereby the incident light on the camera is made possible by a corresponding opening in the mirror housing.
In accord with yet another advantageous embodiment of the invention, the camera is designed to be pivoted, thus increasing its field of regard so that different areas, i.e., fields of view about the vehicle can be brought into view and depicted in the monitor. When backing up is a necessity, then the zone behind the vehicle can be seen in the monitor.
In accord with another advantageous embodiment of the invention, a plurality of cameras is provided. With this multi-camera arrangement, switching among the individual cameras again allows various areas around the vehicle to be presented in the monitor.
If this latter plan is followed, then the pivoting of the camera becomes redundant. The respective camera can be placed in an optimal position, e.g., laterally, to scan the current area to be overseen. The camera for the backing up operation is logically to be installed on the back side of the vehicle.
If additionally a plurality of monitors are available, then under certain circumstances, selective switching from camera to camera becomes unnecessary, since one camera each can be apportioned to one monitor. Additionally, the possibility exists that on various monitors and particularly in different areas of presentation, one monitor can show additional data such as temperature, speed, assured clear distance behind, to the front, or to the side. The different presentation areas of a monitor should be understood in the sense that on the monitor, different items can be selected by the driver and shown by means of an image within an image format.
In accord with a further advantageous embodiment, the rearview mirror can encompass a first and a second monitor. The first monitor is connected with a camera in one rearview mirror, and the second monitor is connected to a camera in the other side rearview mirror of a vehicle. Thus, this arrangement allows a greater area around the vehicle to be scanned at one glance.
By means of an image and data memory apparatus, what is essentially a xe2x80x9cblack-boxxe2x80x9d function is achieved. For this purpose, the continuous images of the last five minutes from one or more cameras can be retained in memory. Additionally, relevant data such as temperature, weather, time, and speed can also be saved. By these means, an accident can be more easily reconstructed.
In accord with another embodiment of the invention, the image recorded by a camera from the mirror housing is angled differently than that of the mirror surface. This is to prevent showing the same image in the monitor as is normally reflected in the mirror.
By means of a digital zoom, that is, by the digital selection and adjustable magnification provided by the zoom, a function and an image component similar to that obtained by the pivoting of a camera are possible.
In accord with another advantageous embodiment, the monitor is integrated into the mirror such that the surface of the monitor is unnoticeable, or scarcely visible when in a non-activated state. This allows the monitor surface to be provided with a partial-reflecting means. Alternately, if the monitor is placed behind the mirror pane, then the area of the mirror pane, behind which the monitor is found, can be likewise be only partially or xe2x80x9chalf-silveredxe2x80x9d with reflecting means. For example, the reflective coating of the mirror pane in an area in front of the monitor is provided with distanced openings in order to obtain a locally higher transparency of the mirror pane. This interruption of the reflecting layer can be, for instance, in the form of thin stripes, relatively parallel to one another. Alternatively, the reflecting coating may be applied in the form of small, individual dots; i.e., stippled. If the reflective area is thus partially opened in such a manner, then the rearview potential of the rearview mirror is only limited by a small degree. Nevertheless, a high degree of local transparency of the mirror pane is gained, so that the monitor, in its activated condition, is visible, although in the non-activated condition, is practically invisible. This reduction of the areal density (i.e., reduced distribution pattern) of the reflective layer can, for instance, be executed by a laser, an etching or inscribing process, or by appropriate masking when the coating is applied to the mirror pane.